Prior to performing any extensive tests of the Thermactor system:
- Be sure that a problem exists.
- Determine that the engine, as a basic unit, is functioning properly by disconnecting the air bypass valve vacuum sensing line at the intake manifold and plugging the manifold connection to prevent leakage.
- Normal engine diagnosis procedures can then be performed.
To test the air supply pump, a test gauge adaptor must be made. Make the adaptor as follows:
- Obtain a 1 / 2 inch pipe T.
- A 2 inch length of 1 / 2 inch galvanized pipe, threaded at one end only.
- A 1 / 2 inch pipe plug.
- A 1 / 2 inch reducer bushing or suitable gauge adaptor.
- Apply sealer to the threads of the 2 inch length of pipe and screw it into one end of the T.
- Apply sealer to the pipe plug and install it into the other end of the T.
- Apply sealer to the threads of the 1 / 2 inch reducer bushing or adaptor for the pressure gauge and install it in the side opening of the T.
- Drill an 11 / 32 inch (0.3437) diameter hole through the center of the pipe plug. Clean out the chips.
- Install a standard fuel pump or other suitable testing gauge into the side opening of the T. The gauge must be graduated in 1 / 4 psi increments.
- Bring the engine to operating temperature.
- Inspect all hoses and connections for leaks. Correct if necessary.
- Check the air pump belt tension; adjust if necessary.
- Disconnect air supply hose(s) at air manifold check valve(s). If there are two valves, block off one hose with a tapered plug; secure the plug with a clamp to prevent blowout.
- Insert the open pipe end of the test gauge adaptor in the other air supply hose. Clamp the hose to the adaptor to prevent blowout.
- Position the adaptor and test gauge so that air discharge from the drilled hole in the adaptor will cause no trouble.
- Connect the tachometer to the engine.
- Start the engine and slowly accelerate to 1,500 rpm. Air pressure registered on the gauge should be greater than 1 psi.
- If the air pressure does not meet or exceed the above pressures, disconnect and plug the air supply hose at the bypass valve. Clamp the plug in place and repeat the pressure test.
- If air pump pressure still does not meet minimum requirements, install a new air pump and repeat the pump test.
- Replace the air pump if necessary.
This test can be performed at the same time as the air pump test.
- Run the engine until it reaches operating temperature.
- Inspect all hoses and connections. Correct any existing leaks before testing the check valve operation.
- Disconnect the air supply hose(s) at the check valve(s).
- Note the position of the valve plate inside the valve body. It should be lightly positioned against the valve seat, away from the air manifold.
- Insert a probe into the hose connection on the check valve and depress the valve plate. It should freely return to its original position against the valve seat when released.
If there are two check valves, check both for freedom of operation.
- With the hose(s) disconnected, start the engine. Slowly accelerate to 1,500 rpm and watch for exhaust leaks at the check valve(s). There should be none. The valve may flutter or vibrate at idle. This is normal, due to exhaust pulsations in the manifold.
- If the check valve(s) does not meet recommended conditions (steps four, five, and six), replace it.
Air Bypass Valve
- Remove the hose that connects the air bypass valve to the air manifold check valve at the bypass valve side.
- With the transmission in Neutral and the parking brake on, start the engine and operate at normal idle speed. Be sure air is flowing from the air bypass valve hose connection. Air pressure should be noted, as this is the normal delivery flow to the air manifold(s).
- Momentarily (for about five seconds), pinch the vacuum hose to the bypass valve. This duplicates the air bypass cycle.
- Release the pinched vacuum hose. Air flow through the air bypass valve should diminish or stop for a short period. The length of time required to resume normal flow cannot be established. Variables in engine vacuum and the length of time the vacuum line is pinched off are determining factors.
Check the bypass valve for diaphragm leakage by performing the following check:
- Remove the vacuum supply hose to the air bypass valve at the bypass valve connection.
- Insert a T-fitting into the vacuum supply hose.
- Connect a vacuum gauge to one of the remaining hose connections on the T.
- Connect a short length of hose (about 3 inches) to the remaining connection.
- Insert a suitable plug in the open end of the short length of hose.
- Start the engine and note the vacuum gauge reading.
- Remove the plug from the short length of hose and connect the hose to the air bypass valve vacuum connection.
- Note the vacuum gauge reading. If the indicated reading does not correspond with the previous reading after about 1 minute, replace the air bypass valve.
REMOVAL & ADJUSTMENT
- Loosen the air pump adjusting bolt. Loosen the air pump-to-mounting bracket bolt and push the air pump toward the cylinder block. Remove the belt.
- Install a new drive belt. With a suitable bar, pry against the rear cover of the air pump to obtain the specified belt tension.
- Then, retighten the pump mounting bolts.
It is highly advisable to use a belt tension gauge to check belt tension. When using this tool, follow the manufacturer's instructions and specifications. Any belt which has been operated for 10 minutes or more is considered to be a used belt, and should be adjusted accordingly.
In the event that a belt tension gauge is not available, the thumb deflection method of belt tension adjustment may be used. This method is discussed in General Information And Maintenance .Air Bypass Valve
See Figure 1
- Disconnect the air and vacuum hoses at the air by-pass valve body.
- Position the air by-pass valve and connect the respective hoses.
- Disconnect the air supply hose at the valve. (Use a 1 1 / 4 inch crowfoot wrench; the valve has a standard, right-hand pipe thread.)
- Clean the threads on the air manifold adaptor (air supply tube on 289 or 302 V8 engine) with a wire brush. Do not blow compressed air through the check valve in either direction.
- Install the check valve and tighten it.
- Connect the air supply hose.
Air ManifoldEXCEPT 289 AND 302 V8
- Disconnect the air supply hose at the check valve, position the hose out of the way, and remove the valve.
- Loosen all of the air manifold-to-cylinder head tube coupling nuts (compression fittings).
- Inspect the air manifold for damaged threads and fittings, and for leaking connections. Repair or replace as required.
- Clean the manifold and associated parts with kerosene. Do not dry with compressed air.
- Position the air manifold(s) on the cylinder head. Be sure all of the tube coupling nuts are aligned with the cylinder head.
- Screw each coupling nut into the cylinder head, 1-2 threads. Tighten the tube coupling nuts.
- Install the check valve and tighten it to specifications.
- Connect the air supply hose to the check valve.
Air Supply Tube289 V8 ENGINES
- Disconnect the air supply hose at the check valve and move the hose out of the way.
- Remove the check valve.
- Remove the air supply tube bolt and seal washer.
- Carefully remove the air supply tube and seal washer from the cylinder head.
- Inspect the air supply tube for evidence of leaking threads or seal surfaces. Examine the attaching bolt head, seal washers, and supply tube surface for leaks. Inspect the attaching bolt and cylinder head threads for damage.
- Clean the air supply tube, seal washers, and bolt with kerosene. Do not dry with compressed air.
- Install the seal washer and air supply tube on the cylinder head. Be sure it is positioned in the same manner as before removal.
- Install the seal washer and mounting bolt. Tighten to specifications.
- Install the check valve, tighten to specifications.
- Connect the air supply hose to the check valve.
Air NozzleEXCEPT 289 AND 302 V8
Normally, air nozzles should be replaced during cylinder head reconditioning. A nozzle may be replaced, however, without removing the cylinder head, by removing the air manifold and using a hooked tool.
Clean the nozzles with kerosene and a stiff brush. Inspect the air nozzles for eroded tips.
Air Pump Filter Fan
- Loosen the air pump as described in earlier procedures.
- Remove the drive pulley attaching bolts and pull the pulley off the air pump shaft.
- Pry the outer disc loose, then remove the centrifugal filter fan. Care must be used to prevent foreign matter from entering the air intake hole, especially if the fan breaks during removal. Do not attempt to remove the metal drive hub.
- Install the new filter fan by drawing it into position with the pulley bolts.
Some 1966-67 air pumps have air filters with replaceable, non-cleanable elements.Air Pump
See Figure 2
- Disconnect the air outlet hose at the air pump.
- Loosen the pump belt tension adjuster.
- Disengage the drive belt.
- Remove the mounting bolt and air pump.
- Position the air pump on the mounting bracket and install the mounting bolt.
- Place the drive belt in pulleys and attach the adjusting arm to the air pump.
- Adjust the drive belt tension to specifications and tighten the adjusting arm and mounting bolts.
- Connect the air outlet hose to the air pump.
Air Pump Relief Valve
Do not disassemble the air pump on the car to replace the relief valve, but remove the pump from the engine.
- Position tool T66L-9A486-D or equivalent, on the air pump and remove the relief valve with the aid of a slide hammer.
- Position the relief valve on the pump housing and hold tool T66L-9A486-B or equivalent, in position.
- Use a hammer to lightly tap the tool until the relief valve is seated.
Relief Valve Pressure-Setting Plug
- Compress the locking tabs inward (together) and remove the plastic pressure-setting plug.
- Before installing the new plug, be sure that the plug is the correct one. The plugs are color-coded.
- Insert the plug in the relief valve hole and push in until it snaps into place.